Acyl piperidyl compounds are disclosed in U.S. Pat. Nos. 3,120,540; 3,640,928 and 3,840,494. U.S. Pat. No. 3,120,540 discloses piperidyl esters of lower dicarboxylic acids having 3 to 6 carbon atoms and quaternary ammonium salts thereof which are pharmacologically active in lowering blood pressure. U.S. Pat. Nos. 3,640,928 and 3,840,494 disclose piperidyl esters of aliphatic, alicyclic, aromatic or heterocyclic dicarboxylic acids. Other related compounds are disclosed in British Pat. No. 1,399,239. These compounds are said to be useful as stabilizers against photo and thermal deterioration of synthetic polymeric materials. U.S. Pat. No. 3,840,494. Thus although piperidyl esters in general have been known, it has now been found that surprisingly and unexpectedly the piperidyl esters of certain acids possess certain unusual properties as compared to the prior art compounds.